Pitfalls and important issues in the pathologic diagnosis of melanocytic tumors.

In Australia and many other countries, melanoma is a major public health problem, particularly in those individuals of Celtic ancestry. Other races are not immune, especially when acral and mucosal sites are taken into account. Accurate diagnosis requires the balancing of clinical data (including patient age and sex, family history, the anatomic site of the lesion, the history of the lesion, and other factors such as a history of trauma, sunburn, or pregnancy), histologic features (including architecture, cytology, and the host response), awareness of pitfalls, and judgment. Several types of nevi-such as regenerating nevi, combined nevi, acral nevi, deep penetrating nevi, and Spitz nevi-are prone to be misdiagnosed as melanoma. Melanomas often underdiagnosed include the nevoid, desmoplastic, Spitzoid, and regressed types. The type of biopsy and suboptimal processing may also significantly influence the diagnosis.